The present method is typically utilized with a cell pack that is being charged by a cell pack charger (in this disclosure, the term "cell pack" is intended to cover batteries, cells, or any similar device which chemically stores an electrical charge), and can detect when the cell pack has reached its fully charged state. A characteristics of many cell packs is that the temperature of the cell pack will remain at a nearly constant level when it is being charged in a discharged state. If the charger is still applying charge to the cell pack in a fully charged state, then the temperature of the cell pack will continue to increase, giving off the energy of the charging electrons in the form of heat. This heat can eventually lead to damage or destruction of the cell pack.
It is recognized in the cell pack art that monitoring the temperature change with respect to time (dT/dt, where T represents the temperature of the cell pack, and t represents the time) provides an accurate method of determining the charge level of the cell pack. Previously, computers have been applied to automate the dT/dt detection. However, in those cases where the sample period (time between successive sampling events) is very small, and/or the time over which the computer is storing dT/dt samples is long, then a large amount of computer storage space (RAM memory) will be required. Since it may be desirable to use a computer which has a small memory, or a larger computer in which much of the memory is being utilized for other purposes, then the prior methods may prove ineffective.
It is evident from the above paragraphs that a method for detecting the charge state of a battery using the dT/dt detector which requires only a relatively small amount of computer memory would be useful and desirable.